diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 5df831ef1442..c7920ba69563 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -299,6 +299,7 @@ ENTRY(secondary_startup_64)
 	pushq	$__KERNEL_CS	# set correct cs
 	pushq	%rax		# target address in negative space
 	lretq
+ENDPROC(secondary_startup_64)
 
 #include "verify_cpu.S"